The remaining infrastructure consists of columns for Period, Revenue, Expense, Net Cash Flow, Discount Factor, Adjusted Cash Flow,Cumulative Cash Flow,and Payback Period. Rows represent each period. Following the conventions in the Chapter 3 model, cells for user input are outlined. These are B3:B4, B7, and B8:C12. We arbitrarily selected a 5-year study period, knowing that we can extend the study period by copying the base formulas down the worksheet.